Light-weight dryer felt seams



arch 21, 1967 D. G. MacBEAN 3,309,790

LIGHT-WEIGHT DRYER FELT SEAMS Filed Oct. 2, 1964 //v VENTO R U. 5.MHCBEAN JLZMVJ Zv.

United States Patent Oil-ice 3,309,790 Patented Mar. 21, .1967

3,309,790 LIGHT-WEIGHT DRYER FELT SEAMS Donald G. MacBean, Pierrefonds,Quebec, Canada, as-

signor to Fabric Research Laboratories Inc., Dedharn Mass.

Filed Oct. 2, 1964, Ser. No. 401,200 Claims priority, applicationCanada, Aug. 21, 1964, 910,062 4 Claims. 01. 34 24s This inventionrelates to light-weight dryer felts for paper machines and particularlyto the method of joining the ends of a relatively thin open-weavefabric.

In the conventional paper machine the web of paper is dried by passingthe web around a series of steam heated dryer drums. A dryer-felt isused in conjunction with these drums to ensure intimate contact. Theconventional felt is a dense impermeable fabric about /8 inch thick, andis joined on the paper machine by means of some form of scam to make itinto an endless belt. One method of joining the ends has been a clipperseam consisting of a series of steel hooked loops which are clenchedinto the fabric. The opposing loops at the joint are brought togetherand the seam completed by the insertion of a pin. Because of thelikelihood of sheet marking, the clipper seam is normally covered with aflap.

Recently a new concept in dryer fabrics has been introduced involvingthe use of an open-weave, relatively thin fabric which will permitevaporating water vapour to escape more readily.

In our co-pending Canadian patent application No. 891,523 filed December17, 1963, I describe one method of forming the joint in an open-weavedryer fabric involving weaving a loop in the ends of the fabric throughwhich a pin can be passed to complete the joint.

In the present application the opposite ends of the openweave fabric arefolded over on themselves and stitched down to form looped ends. Theopposing looped ends of the fabric are then notched in staggeredrelation to each other to permit the projections in either end to fitinto the notches in the opposite ends. A thin fiat pin is then passedthrough the interleaved looped projections to secure the opposite endsof the fabric together. The thin flat pin ensures that the interleavedloop projections will be retained in the same horizontal plane and thelongitudinal length of the projections and the width of the fiat pin aresuch that the finished joint will readily accommodate itself to thecurvature of the dryer drum over which it passes without imparting aridge or other marking to the dryer paper web.

The object of the invention is to provide a joint for light-weight dryerfelt fabrics which will not materially increase the joint thickness overthat of the fabric.

A further object of the invention is to provide a staggered interleavedjoint of flat loop construction with a flat pin to hold the interleavedportions in a common plane.

These and other objects of the invention will be apparent from thefollowing detailed specification and the accompanying drawings, inwhich:

FIG. 1 is a partial perspective view of the opposing ends of the dryerfabric before being joined together and also showing the flat pin beforeinsertion in the joint.

FIG. 2 is a partial plan view of the jointed fabric partly broken awayto show the pin passing through the looped projections.

FIG. 3 is an enlarged plan view of a notched portion of one end of thedryer fabric.

FIG. 4 is a longitudinal section taken on the line 44 of FIG. 3 showingthe method of binding the exposed transverse edges of the notches.

Referring to the drawings, the dryer fabric 5 is formed of a thinopen-weave of warp and weft strands as indicated at 6, in contrast tothe thick dense felt normally used in the manufacture of dryer felts forpaper machines. The warp and weft strands 6 may be made of metal or of aplastic material, or of a combination of metal and plastic strands, forinstance the warp strands may be of a plastic material and the weftstrands may be of metal.

The opposing ends 7 and 8 of the woven fabric are folded over onthemselves as at 9 in FIG. 1, and the folded over portions 9 arestitched together by the stitching 10 to form transverse looped ends asat 11 and 12.

Each folded over end is then notched with a series of notches 13 and 14to form spaced apart projections 15 and 16, each of which forms asection of the loops 11 and 12. The notches 13 in one end of the fabric5 are staggered in relation to the notches 14 in the opposite end of thefabric in order to bring the projections 15 in one end of the fabricinto alignment with the notches 14 in the opposite end of the fabricwhen the two ends of the fabric are brought into opposing relationshipto each other as shown in FIG. 1. Similarly the projections 16 in oneend of the fabric will be aligned with the notches 13 in the opposingend of the fabric. The transverse width of the notches 13 and 14 is suchthat the opposing projections 15 and 16 will fit into the notches with aminimum of clearance space 17 when the two opposing ends of the fabricare interleaved with each other as shown in FIG. 2. Similarly, thelongitudinal depth of the notches 13 and 14, and the projections 15 and16 is such that there will be a minimum of clearance space 18, when thetwo opposing ends of the fabric are interleaved.

The exposed transverse edges 19 of the notches 13 and 14 are heat sealedand the outer ends 20 of the loops 11 and 12 are coated with a suitableplastic 21. This plastic coating 21 will fill the interstices betweenthe warp and weft strands and thereby strengthen the fabric at thesepoints as well as ensuring that the layers of folded over fabric atthese points will not separate. In addition, the coating of plastic 21will tend to fix the length of the loops 11 and 12 in the longitudinallength of the fabric.

A flat key 22 is inserted through the loops 11 and 12 in the opposingprojections 15 and 16, as shown in FIG. 2

to hold the opposing ends of the fabric 5 in the form of a a belt. Theends of the flat key 22 can be headed at 23 in order to retain the keyin place in the joint.

The flat key 22 is a relatively tight fit in the loops of theprojections 15 and 16 when the projections are flattened. The key 22therefore holds the projections 15 and 16 in a common flat plane whenthe joint is assembled.

The key 22 can be perforated as at 24 in order to maintain the porosityof the finish belt throughout the area of the joint.

The longitudinal length of the projections 15 and 16 and the Width ofthe key 22 are such that the assembled joint will have no ridging effectwhen the finished belt is passing around the relatively large diameterof the dryer rolls of the paper machine, and therefore the joint willhave little or no marking effect on the formed paper web.

The folded over end portions 9, being folded over on the same side ofthe fabric ensures that the outer surface 25 of the finished belt willhave a smooth continuous surface on which the formed paper web will becarried while passing through the dryer section of the paper machine.

The key 22 can readily be inserted or withdrawn from the joint when thebelt is being fitted to or being removed from the dryer rolls of thepaper machine, thereby keeping the changeover time. down to a minimum.

What I claim is:

1. A lightweight endless belt for use in the dryer sections of a papermachine, the said belt formed from a length of fabric having an openweave of warp and weft strands, the said length of fabric having itsends joined together to form the endless belt, the joint of the beltcomprising folded over end portions of the fabric stitched to form loopsextending transversely of the fabric, the said looped portions of thefabric having notched out portions forming a series of transverselyspaced apart looped projections, the projections in one end of thefabric being staggered in relation to the projections of the oppositeend of the fabric with the projections in one end of the fabricinterleaving with the notched out portions in the opposite end of thefabric when the ends of the fabric are brought together to form theendless belt, and a key fitted through the interleaved loopedprojections to secure the joint of the belt, the said key having aseries of perforations throughout its length to maintain the porosity ofthe belt throughout the area of the joint.

2. A lightweight endless belt as set forth in claim 1,

in which the said key fiat is a fiat strip having its ends headed tosecure the key in the joint.

3. A lightweight endless belt as set forth in claim 1, in which theexposed edges of the folded over fabric between the looped projectionsare heat sealed.

4. A lightweight endless belt as set forth in claim 1, in which thefolded over fabric adjacent the base of the notches and projections iscoated with a plastic material, the said plastic material penetratingthe interstices of the Woven fabric to bond the folded over endportions.

References Cited by the Examiner UNITED STATES PATENTS 2,005,979 6/1935Milnes 24-33 2,084,490 6/1937 Hooper 24-33 2,814,845 12/1957 Hjort 2433FOREIGN PATENTS 929,951 7/ 1947 France.

KENNETH W. SPRAGUE, Primary Examiner.

1. A LIGHTWEIGHT ENDLESS BELT FOR USE IN THE DRYER SECTIONS OF A PAPERMACHINE, THE SAID BELT FORMED FROM A LENGTH OF FABRIC HAVING AN OPENWEAVE OF WARP AND WEFT STRANDS, THE SAID LENGTH OF FABRIC HAVING ITSENDS JOINED TOGETHER TO FORM THE ENDLESS BELT, THE JOINT OF THE BELTCOMPRISING FOLDED OVER END PORTIONS OF THE FABRIC STITCHED TO FORM LOOPSEXTENDING TRANSVERSELY OF THE FABRIC, THE SAID LOOPED PORTIONS OF THEFABRIC HAVING NOTCHED OUT PORTIONS FORMING A SERIES OF TRANSVERSELYSPACED APART LOOPED PROJECTIONS, THE PROJECTIONS IN ONE END OF THEFABRIC BEING STAGGERED IN RELATION TO THE PROJECTIONS OF THE OPPOSITEEND OF THE FABRIC WITH THE PROJECTIONS IN ONE END OF THE FABRICINTERLEAVING WITH THE NOTCHED OUT PORTIONS IN THE